Recent technological developments and increased public awareness of the need for routine mammographic screening have resulted in a dramatic increase in the detection of small, often nonpalpable breast lesions. Unfortunately, the pace of development of surgical tools has not kept pace with development of the diagnostic tools and removal of these small lesions remains a difficult, time consuming process that is prone to failure. The system described in this proposal is intended to allow surgeons to accurately identify the position of tumor margins during breast conservation surgery and needle-localization breast biopsy procedures. The system is intended to increase the accuracy of these procedures and reduce the number of surgeries that fall due to incomplete resections or missed lesions. In Phase I, a prototype distance-measuring probe will be constructed and tested in a series of simulated surgical resections. In Phase II, a handheld version of the system will be developed and tested in vivo. PROPOSED COMMERCIAL APPLICATIONS: The commercial potential of a cost-effective system to improve the outcome of breast conservation surgeries is significant. Our commercialization strategy is based on licensing the technology developed under this program to an existing vendor of medical equipment.